Hearing devices are wearable hearing apparatuses which are used to assist the hard-of-hearing. In order to accommodate numerous individual requirements, various types of hearing devices are available such as behind-the-ear hearing device (BTEs), hearing device with an external receiver (RIC: receiver in the canal) and in-the-ear hearing devices (ITE), for example also concha hearing devices or completely-in-the-canal hearing devices (ITE, CIC). The hearing devices listed as examples are worn on the outer ear or in the auditory canal. Bone conduction hearing aids, implantable or vibrotactile hearing aids are also available on the market. In these devices damaged hearing is stimulated either mechanically or electrically.
The key components of hearing devices are principally an input converter, an amplifier and an output converter. The input converter is normally a receiving transducer e.g. a microphone and/or an electromagnetic receiver, e.g. an induction coil. The output converter is most frequently realized as an electroacoustic converter e.g. a miniature loudspeaker, or as an electromechanical converter e.g. a bone conduction hearing aid. The amplifier is usually integrated into a signal processing unit. This basic configuration is illustrated in FIG. 1 using the example of a behind-the-ear hearing device. One or a plurality of microphones 2 for recording ambient sound are built into a hearing device housing 1 to be worn behind the ear. A signal processing unit 3 which is also integrated into the hearing device housing 1 processes and amplifies the microphone signals. The output signal for the signal processing unit 3 is transmitted to a loudspeaker or receiver 4, which outputs an acoustic signal. Sound is transmitted through a sound tube, which is affixed in the auditory canal by means of an otoplastic, to the device wearer's eardrum. Power for the hearing device and in particular for the signal processing unit 3 is supplied by means of a battery 5 which is also integrated in the hearing device housing 1.
Hearing devices are very sensitive devices which may however be subject to relatively aggressive environments. It is not only the high air humidity which has to be considered here but also the sweat produced by a hearing device wearer and more aggressive gases and vapors to which the hearing device wearer is exposed at times. Aggressive environmental conditions of this type frequently result in electrical components of the hearing device corroding. Corresponding farms and coatings of hearing device housings were therefore previously proposed in order to prevent aggressive substances from penetrating the hearing device housing.
The publication DE 199 03 090 A1 discloses a waterproof hearing aid. It includes a housing with a battery compartment as well as a sound outlet opening. The battery compartment is sealed from the remaining housing in a waterproof fashion. The sound outlet opening is sealed by an acoustically permeable, waterproof film.
The publication DE 195 02 994 C2 discloses a similarly waterproof hearing aid, which includes a housing with a ventilation opening. A waterproofing facility blocks the ventilation opening and is used to allow air to enter but to prevent the penetration of humidity.